It was a romantic anniversary for Michael Kauffman, 25 years to the day since he first met his wife. Yet there he stood in front of a mausoleum in the middle of Woodland Cemetery in Des Moines with four strangers on a chilly, murky afternoon as a steady rain began to fall.

It was just the latest stop in Kauffman's quest to flesh out the entire universe of characters surrounding the assassination of President Abraham Lincoln.

Our 16th president was shot 150 years ago — April 14, 1865 — by the dashing 26-year-old actor John Wilkes Booth at Ford's Theatre in Washington, D.C. Lincoln was pronounced dead the following morning.

By day, Kauffman, 58, who lives in the Maryland outskirts of the nation's capital, is operations manager for a nonprofit broadcasting company.

But his true passion is combing through Civil War soldier pension files, death certificates and other remnants of the past to chronicle and cross-reference this signature national tragedy in meticulous detail.

He continues to cultivate his own vast database of 3,400 people connected to the assassination.

The Assassination of President Lincoln at Ford's Theatre, Washington, DC, April 14, 1865 Illustration showing John Wilkes Booth shooting President Abraham Lincoln.(Photo: Library of Congress)

Thus far Kauffman has visited the graves of probably 1,800 of those characters — more than half.

Earlier this week in the cemetery he clutched a compact spiral notebook and had a camera slung around his neck.

He used his iPhone to plot the GPS coordinates, as he does for each grave site.

"As I get older I learn to keep better records," Kauffman said.

He flew to Des Moines primarily to deliver the keynote address for last weekend's Des Moines Civil War Roundtable 50

th Anniversary Gala at the State Historical Museum.

A conspiracy, long planned and carefully executed, makes President Abraham Lincoln one of the final casualties of the Civil War. Actor and Confederate sympathizer John Wilkes Booth had plotted against Lincoln for the better part of a year before fatally shooting him at Ford's Theatre.(Photo: Library of Congress Prints and Photographs Division)

But he's a restless sort — often awake before dawn to hit the road for his research. And he wanted to take full advantage of his time here. So he rented a car to wander hundreds of miles to a dozen or more graves in Iowa, Illinois, Missouri and Minnesota.

He visited the final resting place of Robert Hamilton Cooper in Winterset, a man who swore he saw conspirator and Confederate spy John Surratt outside Ford's Theatre on the day of the assassination and thus became a key trial witness.

Gov. William Milo Stone, buried in Knoxville, was Iowa's sixth governor and claimed he helped carry Lincoln out of the theater (a claim yet to be verified).

President Abraham Lincoln's top hat, Brooks Brothers Coat, and and items from his pockets from the night of his assassination are displayed at the Ford's Center for Education and Leadership in Washington, D.C.(Photo: AP Photo/Andrew Harnik)

Kauffman made other stops in Grinnell, Keokuk, etc.

"It's an experience that sets it fully in my memory," he explained of his epic tombstone tours. Otherwise all his historical characters tend to just jumble together as so many names on lists.

"History, it's people," he said. "It's just people. If you study the people, you get the story."

A few months ago, Kauffman was in Jackson, Mich., at the grave site of Christian Rath, a great name for the guy who hanged four convicted Lincoln assassination conspirators.

Last week found him in Troy, N.Y. Next week he flies to Paris, where he intends to trace the footsteps of Surratt, who fled to Europe.

"Everywhere I go it seems I run into connections," Kauffman said last week during his first Iowa stop, a quick book-signing Friday afternoon at Beaverdale Books.

President Abraham Lincoln's top hat from the night of his assassination is on display at a new exhibit entitled "Silent Witnesses: Artifacts of the Lincoln Assassination" at the Ford's Center for Education and Leadership across the street from the historic Ford's Theatre where President Abraham Lincoln was killed, in Washington.(Photo: AP Photo/Andrew Harnik)

You've heard of the "Six Degrees of Kevin Bacon" game, how nearly anybody can be connected to the movie actor within half a dozen or fewer steps? Kauffman typically needs just two or three steps to link a person or place to the Lincoln assassination.

He cited the Beatles as an example: Booth's sister lived at the address in London that later became Abbey Road Studios.

What about Iowan John Wayne? Raoul Walsh portrayed John Wilkes Booth in 1915's "The Birth of a Nation" — and went on to direct Wayne in his first starring role in 1930's "The Big Trail." When producers pushed Marion Morrison to adopt a bold Hollywood pseudonym, it was Walsh who came up with "Wayne," inspired by a Revolutionary War general.

Kauffman was born in Allentown, Pa. He grew up the son of a career Marine and moved around a lot with his family. From an early age he sensed the deep-seated cultural divide that lingered as he lived both north and south of the Mason-Dixon line.

Local Lincoln experts Lowell and Rhoda Sneller of West Des Moines, who 20 years ago created abrahamlincolnonline.org, first met Kauffman in 2002. They embarked on the author's elaborate John Booth Escape Route Tour that traced the killer's 12 days on the lam from Ford's Theatre to a burning tobacco barn in Virginia.

"He goes beyond what the average, say, university professor might do in terms of research," Rhoda Sneller said.

Kauffman has leaped out of the box where Lincoln sat at Ford's Theatre and onto the stage, mimicking Booth. He has rowed across the Potomac River. He has burned down a barn.

Author provided John Wilkes Booth, who assassinated President Abraham Lincoln.(Photo: Special to the Register)

All this exhaustive research seems to have given Kauffman a rich, nuanced understanding of his main character, whom he describes as a cunning, deceitful man.

"Knowing what I know about him now," he said of Booth, "if he said 'hello' I wouldn't believe him."

So Kauffman's Iowa trail brought him finally to Woodland Cemetery and the Casady mausoleum. He had just driven in from St. Louis (where he had met up with his wife).

The old stone vault also is the final resting place for Iowa Rep. John Adam Kasson, who died in 1910. Kasson "claimed to have attended a reception at the Seward House, where he was handled roughly by would-be assassin Lewis Powell," Kauffman had written in notes to John Liepa, a retired Des Moines Area Community College history professor who helps organize the Civil War Roundtable.

Liepa and Kauffman were joined in the cemetery by Cap and Patricia Casady. Judge Phineas Casady was Cap's great-great-grandfather. The couple brought a set of keys to the mausoleum that they hadn't opened in years. Extra padlocks prevented them from getting inside. Kauffman had to content himself with receiving emailed photos later on.

Kauffman was enthusiastic about his first scouring of Iowa. He was able to meet Ron Rietveld of Pella, who was 14 years old in 1952 when he discovered the only known photo of Lincoln after death. Kauffman even found time for a detour stop at the Buddy Holly crash site north of Clear Lake.

I'm willing to bet that nobody has spent more time researching a single event in any president's life — JFK zealots included — than this guy.

John Wilkes Booth's pistol used to kill President Abraham Lincoln is displayed at an exhibit at the Ford's Center for Education and Leadership.(Photo: AP Photo/Andrew Harnik)

"We met on the Booth escape tour," Kauffman said of his wife as he climbed into his rental car. "I had to marry somebody who would tolerate all this."

Booth killed Lincoln with a single shot. Apparently that also was a starting gun that belatedly triggered Kauffman's historical marathon that won't end until the cemetery grave he's visiting is his own.